The present disclosure relates to three-dimensional (3D) printing, and more specifically to 3D printing of ceramics.
3D printing includes various processes to make 3D objects. Computer control is used to lay successive material layers, using a 3D model or other electronic data source to make resulting 3D objects with any shape or geometry.
Originally, the term 3D printing referred to processes that sequentially deposited layers of material onto a powder bed with inkjet printer heads. More recently, however, the definition of 3D printing has expanded to encompass a wider variety of techniques, such as extrusion and sintering-based processes. Technical standards generally use the term “additive manufacturing” for this broader sense. Binder jetting, robocasting, and fused/filament deposition modeling (FDM) are also examples of such additive manufacturing methods.
Binder jetting involves depositing an organic binder solution onto a powder bed to build up ceramic articles, layer by layer. Although binder jetting can achieve complex geometries, it cannot fabricate intricate internal patterns, channels, or honeycombs due to entrapped powder in the resulting article.
Robocasting uses the Newtonian behavior of ceramic slurries to print ceramic articles with an extruded paste. The ceramic slurry viscosity drops as it is sheared by the extrusion process. Once the paste is extruded, the shear stress on the material decreases, and the viscosity rises, returning the extrusion to a thick paste consistency. Successive layers are built-up based upon the nozzle geometry. Although robocasting can produce hollow honeycomb features, the printed ceramic article's resolution is coarse, and high density sintered ceramics cannot be obtained.
FDM uses a plastic filament or metal wire, which is unwound from a coil, to supply material to an extrusion nozzle. The nozzle is heated to melt the material, which hardens immediately after extrusion.